A domain can only be connected to one form at a time. If you try to add a domain that is already in use by another form, you will see the error: 'Cannot add {domain} since it is already in use.' To move a domain to a different form, remove it from the current form first.
Use different subdomains on the same root domain, each connected to a different form. For example:
quote.yourbrand.com → your quote form
book.yourbrand.com → your booking form
refer.yourbrand.com → your referral form
At your registrar, add a separate A record for each subdomain — e.g. host: quote, value: 216.150.1.1; host: book, value: 216.150.1.1.
In Connect → Deploy of each form, add the relevant subdomain.
Each form verifies independently. Once verified, each subdomain routes visitors to its own form.